Link Between Cavitation Development and Erosion Damage in Diesel Injector Nozzles

Gavaises, Manolis; Papoulias, D.; Andriotis, A.; Giannadakis, E.; Theodorakakos, A.

doi:10.4271/2007-01-0246

Cited by 52 publications

(46 citation statements)

References 16 publications

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“…Highly transient flow phenomena caused by the fast needle response times, give rise to formation of vortical structures and therefore, to string cavitation [8]. Transient effects have also been correlated to increased probability of surface erosion damage, which is attributed to both, geometric and string cavitation [29]. Unfortunately, all relevant studies so far report data from one or just a few injection events.…”

Section: Introductionmentioning

confidence: 90%

Instantaneous and ensemble average cavitation structures in Diesel micro-channel flow orifices

Mitroglou

McLorn

Gavaises

et al. 2014

Fuel

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Section: Introductionmentioning

confidence: 90%

Instantaneous and ensemble average cavitation structures in Diesel micro-channel flow orifices

Mitroglou

McLorn

Gavaises

et al. 2014

Fuel

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“…The nozzle itself is a VCO design which implies that the needle valve seals directly in the hole entry area, thus eliminating the dead volume below the injection holes. A recent study by Gavaises et al 29 reported cavitation images and fluid dynamics predictions for two VCO nozzles identical with that used in the present study but with cylindrical holes; emphasis was placed in that study on the effect of two different needle designs which has been found to influence nozzle cavitation and erosion. The present investigation focuses on the shape of the injection holes.…”

Section: Experimental Setup and Test Casesmentioning

confidence: 99%

“…A scanning electron microscope ͑SEM͒ picture of the actual injector reported recently in Ref. 29 and also shown here in Fig. 8͑c͒ indicates that cavitation strings may also be responsible for cavitation erosion.…”

Section: -5mentioning

confidence: 99%

Characterization of string cavitation in large-scale Diesel nozzles with tapered holes

et al. 2009

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This is the published version of the paper.This version of the publication may differ from the final published version. The cavitation structures formed inside enlarged transparent replicas of tapered Diesel valve covered orifice nozzles have been characterized using high speed imaging visualization. Cavitation images obtained at fixed needle lift and flow rate conditions have revealed that although the conical shape of the converging tapered holes suppresses the formation of geometric cavitation, forming at the entry to the cylindrical injection hole, string cavitation has been found to prevail, particularly at low needle lifts. Computational fluid dynamics simulations have shown that cavitation strings appear in areas where large-scale vortices develop. The vortical structures are mainly formed upstream of the injection holes due to the nonuniform flow distribution and persist also inside them. Cavitation strings have been frequently observed to link adjacent holes while inspection of identical real-size injectors has revealed cavitation erosion sites in the area of string cavitation development. Image postprocessing has allowed estimation of their frequency of appearance, lifetime, and size along the injection hole length, as function of cavitation and Reynolds numbers and needle lift. Permanent repository link

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“…Further increase of injection pressure up to 2500/3000 bar is expected to put less demand on the aftertreatment systems and result to overall cheaper solution for the whole powertrain. However, increased pressure and multiple injections make the FIE sensitive and vulnerable to cavitation erosion damage [2,3]. As a result, more accuracy is also needed to the predictive tools employed for the design of such systems.…”

Section: Background and Motivationmentioning

confidence: 99%

“…The most promising ones are based on the assumption that cavitation is a mechanically driven phenomenon initiated by the presence of cavitation nuclei which grow to become bubbles and then to form the complex two-phase flow structures observed macroscopically in studies employing transparent nozzle (selectively [2,[13][14][15][16][17][18][19][20][21][22][23][24][25][26][27]). Starting from this basic assumption, the transport of vapour can be treated either as a continuous cloud, and thus simulated on an Eulerian frame of reference, or as discrete vapour/air bubbles which are tracked using an Eulerian-Lagrangian approximation.…”

Section: Cavitation Model Descriptionmentioning

confidence: 99%

Simulation of Heating Effects Caused by Extreme Fuel Pressurisation in Cavitating Flows through Diesel Fuel Injectors

Gavaises¹,

Theodorakakos

Mitroglou³

2012

Proceedings of the 8th International Symposium on Cavitation

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Pressurization of Diesel fuel in modern common-rail injectors in excess of 2000bar can result to increased temperatures and significant variation of the fuel physical properties (density, viscosity, heat capacity and thermal conductivity) relative to those under atmospheric pressure and room temperature conditions. Moreover, due to the sharp de-pressurization experienced by the fuel at the inlet of the injection holes, significant gradients of the above properties are established. The subsequent fuel acceleration at velocities reaching 700m/s is also inducing further wall friction and thus heating. Consequently, the characteristics of cavitation taking place at the entrance to the injection holes are altered while the volumetric efficiency of the nozzle is significantly affected. The present study quantifies the role of these effects in mini sac-type Diesel injectors operating at pressures up to 2400bar through use of a RANS cavitation CFD model. The flow solver is accordingly modified to account for such effects during the solution of the flow conservation equations. Two different injector designs have been considered, both based on the same mini sac-type nozzle body; one with sharp-inlet cylindrical holes and one with tapered holes with inlet rounding. The results indicate significant changes in terms of the details of the flow development but also to bulk flow characteristics such as the volumetric efficiency of the injectors and the mean fuel injection temperature relative to the isothermal/constant properties case.

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Link Between Cavitation Development and Erosion Damage in Diesel Injector Nozzles

Cited by 52 publications

References 16 publications

Instantaneous and ensemble average cavitation structures in Diesel micro-channel flow orifices

Instantaneous and ensemble average cavitation structures in Diesel micro-channel flow orifices

Characterization of string cavitation in large-scale Diesel nozzles with tapered holes

Simulation of Heating Effects Caused by Extreme Fuel Pressurisation in Cavitating Flows through Diesel Fuel Injectors

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